linux-kernel - Re: [PATCH v4] bus: mhi: core: Handle syserr during power

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Date:   Thu, 14 May 2020 10:53:05 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Jeffrey Hugo <jhugo@...eaurora.org>
Cc:     hemantk@...eaurora.org, bbhatt@...eaurora.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] bus: mhi: core: Handle syserr during power_up

On Thu, May 07, 2020 at 10:19:31AM -0600, Jeffrey Hugo wrote:
> The MHI device may be in the syserr state when we attempt to init it in
> power_up().  Since we have no local state, the handling is simple -
> reset the device and wait for it to transition out of the reset state.
> 
> Signed-off-by: Jeffrey Hugo <jhugo@...eaurora.org>

Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>

Will apply this patch to mhi-next and include in the 5.8 series.

Thanks,
Mani

> ---
> 
> v4:
> -Implemented Hemant's suggested solution from v2.  The spec will be amended
> to indicate the intvec interrupt will be triggered for the reset state change
> which matches the current implementations and enables Hemant's solution to
> be used, which is cleaner.
> 
>  drivers/bus/mhi/core/pm.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/drivers/bus/mhi/core/pm.c b/drivers/bus/mhi/core/pm.c
> index dc83d65..ddef693 100644
> --- a/drivers/bus/mhi/core/pm.c
> +++ b/drivers/bus/mhi/core/pm.c
> @@ -760,6 +760,7 @@ static void mhi_deassert_dev_wake(struct mhi_controller *mhi_cntrl,
>  
>  int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
>  {
> +	enum mhi_state state;
>  	enum mhi_ee_type current_ee;
>  	enum dev_st_transition next_state;
>  	struct device *dev = &mhi_cntrl->mhi_dev->dev;
> @@ -829,6 +830,32 @@ int mhi_async_power_up(struct mhi_controller *mhi_cntrl)
>  		goto error_bhi_offset;
>  	}
>  
> +	state = mhi_get_mhi_state(mhi_cntrl);
> +	if (state == MHI_STATE_SYS_ERR) {
> +		mhi_set_mhi_state(mhi_cntrl, MHI_STATE_RESET);
> +		ret = wait_event_timeout(mhi_cntrl->state_event,
> +				MHI_PM_IN_FATAL_STATE(mhi_cntrl->pm_state) ||
> +					mhi_read_reg_field(mhi_cntrl,
> +							   mhi_cntrl->regs,
> +							   MHICTRL,
> +							   MHICTRL_RESET_MASK,
> +							   MHICTRL_RESET_SHIFT,
> +							   &val) ||
> +					!val,
> +				msecs_to_jiffies(mhi_cntrl->timeout_ms));
> +		if (ret) {
> +			ret = -EIO;
> +			dev_info(dev, "Failed to reset MHI due to syserr state\n");
> +			goto error_bhi_offset;
> +		}
> +
> +		/*
> +		 * device cleares INTVEC as part of RESET processing,
> +		 * re-program it
> +		 */
> +		mhi_write_reg(mhi_cntrl, mhi_cntrl->bhi, BHI_INTVEC, 0);
> +	}
> +
>  	/* Transition to next state */
>  	next_state = MHI_IN_PBL(current_ee) ?
>  		DEV_ST_TRANSITION_PBL : DEV_ST_TRANSITION_READY;
> -- 
> Qualcomm Technologies, Inc. is a member of the
> Code Aurora Forum, a Linux Foundation Collaborative Project.